A police officer suspended from duty after a video showing a man being repeatedly punched in the head during an arrest in Porthmadog went viral is under criminal investigation.

The officer, who has not been named, has been served with a gross misconduct notice after the video showed him with his arm around a man's neck while appearing to punch him in the his face.

The Independent Office for Police Misconduct (IOPC) said the officer had been suspended by North Wales Police.

It said a second officer had been also served with a misconduct notice.

The IOPC website states the following: "The Independent Office for Police Conduct (IOPC) investigation into the use of force during the arrest of a man in Porthmadog is progressing.

"We began our investigation the day after the incident involving North Wales Police last month, after a referral from the force.

"We have established that at around 11 am on 10 May, two officers were sent to a reported disturbance at an address in the town.

"At about 11.50am the officers located a man in the garden of a nearby house and arrested him. Footage shows an officer striking the man to his head a number of times, while on the ground.

"The same officer used incapacitant spray towards the man as he was being placed in the rear of a police van.

"While en route to the police station, it was noticed that the man appeared to be unwell and was given first aid.

"He was then taken by ambulance to hospital and was later released back into police custody.

"We have examined police body worn video and phone footage of the incident, taken witness statements including from the injured man, and located relevant CCTV footage.

"We are examining whether the force used was justifiable, proportionate and necessary, if the aftercare provided following arrest was appropriate, and whether the officers acted in accordance with their training and followed North Wales Police’s policies and procedures. North Wales Police are cooperating fully with our enquiries."

IOPC Director David Ford said: “There has been considerable interest and public concern over the footage shared widely on social media, which shows some of the interaction between police officers and the man being arrested. We are progressing our investigation in a thorough and timely manner, carefully securing and examining a range of evidence to establish what took place during the whole incident.

“Based on the evidence we have reviewed so far, we have notified a police constable that they are under criminal investigation and have served them a gross misconduct notice.

"This does not necessarily mean that criminal or disciplinary proceedings will follow.

"We understand the officer has been suspended by North Wales Police. We have also served a misconduct notice on another police constable concerning the level of care provided to the man after his arrest.”